Multilayered screens for scanning beam display systems

ABSTRACT

A display screen includes a filter layer, a fluorescent layer having parallel fluorescent stripes, and an attachment layer between an excitation side of the fluorescent layer and a first side of the filter layer to attach the excitation side of fluorescent layer to the filter layer while providing vertical separation therebetween. The attachment layer includes attachment regions that are separated from each other by lateral spacings such that excitation-side air gaps are formed between areas of the fluorescent layer and the filter layer that correspond to the lateral spacings. During display operation, excitation light received on a second side of the filter layer propagates through to the first side of the filter layer, and at least a portion of the excitation light that propagates from the second side of the filter layer travels through the excitation-side air gaps to excite the fluorescent stripes.

TECHNICAL FIELD

This application generally relates to multilayered fluorescent screensfor use in display systems that scan one or more optical beams onto ascreen to display images.

BACKGROUND

Display systems can be configured to use screens with fluorescentmaterials to emit colored light under optical excitation, such aslaser-based image and video displays and screen designs for suchdisplays.

Image and video displays can be designed to directly produce light ofdifferent colors that carry color images and to project the color imageson a screen, where the screen makes the color images visible to a viewerby reflection, diffusion, or scattering of the received light and doesnot emit light. Examples of such displays include digital lightprocessing (DLP) displays, liquid crystal on silicon (LCoS) displays,and grating light valve (GLV) displays. Some other image and videodisplays may use a light-emitting screen that produces light ofdifferent colors to form color images. Examples of such display systemsinclude cathode-ray tube (CRT) displays, plasma displays, back-litliquid crystal displays (LCDs), light-emitting-diode (LED) displays(e.g., organic LED displays), and field-emission displays (FEDs).

SUMMARY

According to one aspect, a display screen includes a filter layer havinga first side and an opposing second side, a fluorescent layer includinga plurality of parallel fluorescent stripes, and an attachment layerpositioned between an excitation side of the fluorescent layer and thefirst side of the filter layer to attach the excitation side offluorescent layer to the filter layer while providing verticalseparation between the fluorescent layer and the filter layer. Theattachment layer includes a plurality of attachment regions that areseparated from each other by one or more lateral spacings such that oneor more excitation-side air gaps are formed between areas of thefluorescent layer and the filter layer that correspond to the one ormore lateral spacings in the attachment layer. During display operation,excitation light received on the second side of the filter layerpropagates through to the first side of the filter layer, and at least aportion of the excitation light that propagates from the second side ofthe filter layer travels through the one or more excitation-side airgaps to excite the fluorescent stripes.

Implementations according to this aspect may include one or more of thefollowing features. For example, the attachment layer may include aplurality of attachment stripes that contact the excitation side of thefluorescent stripes at their edge regions. The plurality of attachmentstripes may extend parallel to the fluorescent stripes. The plurality ofattachment stripes may bridge spaces between adjacent fluorescentstripes. In some cases, the plurality of attachment stripes may extendtransverse to the fluorescent stripes. The attachment layer may beformed from a UV-curable resin. The attachment regions may be positionedto not overlap with center regions of the fluorescent stripes. Theplurality of fluorescent stripes may be spaced apart from each othersuch that in-plane air gaps are formed between adjacent fluorescentstripes. In some cases, the display screen may also include a sheetlayer having a first side and an opposing second side, and an adhesivelayer positioned between a viewer side of the fluorescent layer and thesecond side of the sheet layer to attach the viewer side of fluorescentlayer to the sheet layer while providing vertical separation between thefluorescent layer and the sheet layer, the adhesive layer definingopenings such that one or more viewer-side second air gaps are formedbetween areas of the fluorescent layer and the sheet layer thatcorrespond to the one or more openings in the adhesive layer, wherein,during display operation, at least a portion of the fluorescent lightthat emanates from the fluorescent layer travels through the one or moreviewer-side air gaps.

The display screen according to this aspect may also include a sheetlayer having a first side and an opposing second side, and an adhesivelayer positioned between a viewer side of the fluorescent layer and thesecond side of the sheet layer to attach the viewer side of fluorescentlayer to the sheet layer while providing vertical separation between thefluorescent layer and the sheet layer, the adhesive layer definingopenings such that one or more viewer-side air gaps are formed betweenareas of the fluorescent layer and the sheet layer that correspond tothe one or more openings in the adhesive layer, wherein, during displayoperation, at least a portion of the fluorescent light that emanatesfrom the fluorescent layer travels through the one or more viewer-sideair gaps. The adhesive layer may have an anti-aliasing patternconfigured to reduce moiré patterns in an image displayed on the displayscreen. The plurality of fluorescent stripes may be spaced apart fromeach other such that in-plane second air gaps are formed betweenadjacent fluorescent stripes. The adhesive layer may include across-hatch pattern. The adhesive layer may include a sinusoidalpattern. The attachment layer may include a plurality of attachmentstripes that extend perpendicular to the fluorescent stripes. Theattachment layer may include a plurality of attachment posts arenarrower in width than the in-plane gaps that separate the fluorescentstripes.

According to another aspect, a display screen includes a filter layerhaving a first side and an opposing second side, a fluorescent layerincluding a plurality of parallel fluorescent stripes, and an attachmentlayer positioned between an excitation side of the fluorescent layer andthe first side of the filter layer to attach the excitation side offluorescent layer to the filter layer while providing verticalseparation between the fluorescent layer and the filter layer, theattachment layer including a plurality of attachment regions thatunderlie a first region of the fluorescent stripes and that areseparated from each other by one or more lateral spacings. One or moreexcitation-side low-index gaps are formed in the one or more lateralspacings in between areas of the fluorescent layer and the filter layer,the low-index gaps underlying a second region of the fluorescent stripesdifferent from the first region of the fluorescent stripes. Duringdisplay operation, excitation light received on the second side of thefilter layer propagates through to the first side of the filter layer,and at least a portion of the excitation light that propagates from thesecond side of the filter layer travels through the one or moreexcitation-side low-index gaps to excite the fluorescent stripes.

Implementations of this aspect may include one or more of the followingfeatures. For example, the low-index air gaps may partially underliespaces between adjacent fluorescent stripes. The low-index air gaps mayoccupy spaces between adjacent fluorescent stripes. In some cases, thelow-index gaps may be air gaps.

Potential advantages may include one or more of the following. Placementof an air gap above and below the phosphor layer can increase brightnessand reduce cross-talk. Ambient contrast can be improved. The air gapscan be manufactured reliably with uniform stand-off fromdevice-to-device.

The details of one or more embodiments are set forth in the accompanyingdrawings and the description below. Other aspects, features andadvantages will be apparent from the description, drawings and claims.

DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram of an example scanning beam display systemhaving a screen having fluorescent stripes.

FIG. 2A is a schematic cross-sectional side view of the screen in FIG.1.

FIG. 2B is a schematic close-up front view of the screen in FIG. 2Aalong the direction B-B.

FIG. 3 is a schematic diagram of an example implementation of the lasermodule in FIG. 1 having multiple lasers that direct multiple laser beamson the screen.

FIG. 4 is a schematic exploded cross-sectional side view of an examplescreen having a fluorescent stripe layer with fluorescent stripes foremitting red, green and blue colors under optical excitation of thescanning excitation light.

FIG. 5 is a schematic perspective view of a portion of an example screenhaving fluorescent stripes supported above a substrate.

FIG. 6 is a schematic cross-sectional side view of the fluorescentscreen in FIG. 5.

FIGS. 7A-7H are schematic bottom views illustrating various locationsand shapes for the attachment layer relative to the fluorescent stripes.

FIG. 8 is a schematic perspective view of a portion of an example screenhaving an adhesive layer above the fluorescent stripes.

FIGS. 9A-9D are schematic top views illustrating various patterns forthe adhesive layer above the fluorescent stripes.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

Display systems that use screens with fluorescent materials to emitcolored light under optical excitation can be implemented in variousconfigurations. For example, fluorescent materials can be included in ascreen to absorb the light of the one or more scanning optical beams andto emit new light that forms the images. The fluorescent materialsconvert excitation energy applied to the screen into the emitted visiblelight, e.g., via absorption of excitation light. The emitted visiblelight forms images visible to a viewer.

Objectives for a commercial display screen include brightness andcontrast. Supporting the fluorescent layer with an air gap between thefluorescent layer and the underlying support substrate can increasebrightness and reduce cross-talk. Without being limited to anyparticular theory, the air gap can decrease internal absorption of lightemitted from the fluorescent layer at large angles relative to thedirection normal to the screen surface. This can reduce the likelihoodof emitted light crossing into adjacent pixels, and thus can reducecross-talk and improve contrast. Similarly, since more emitted light isinternally reflected back toward the viewer side of the screen,brightness can be increased. Moreover, the air gap can reduce the amountof the emission that is coupled to the supporting substrate. Otherwise,the coupled emission may propagate in the supporting substrate and causeexcitation of adjacent phosphor layers.

Scanning beam display systems using such a light-emitting screens caninclude fluorescent materials arranged to provide a pattern oflight-emitting regions that emit light for forming images andnon-light-emitting regions that are spaces void of light-emittingmaterials between the light-emitting regions. The pattern of thelight-emitting regions and non-light-emitting regions can be in variousconfigurations, e.g., one or more arrays of parallel light-emittingstripes, one or more arrays of isolated light-emitting island-likeregions or pixel regions, or other design patterns. The geometries ofthe light-emitting regions can be various shapes and sizes, e.g.,squares, rectangles or stripes. Examples described below use alight-emitting screen that has parallel light-emitting stripes separatedby non-light-emitting lines located between the light-emitting stripes.Each light-emitting stripe can include a light-emitting material such asa phosphor-containing material that either forms a contiguous stripeline or is distributed in separated regions along the stripe.

In some implementations, three different color phosphors or phosphorcombinations that are optically excitable by the laser beam torespectively produce light in red, green, and blue colors suitable forforming color images may be formed on the screen as pixel dots orrepetitive red, green and blue phosphor stripes in parallel. Variousexamples described in this application use screens with parallel colorphosphor stripes for emitting light in red, green, and blue toillustrate various features of the laser-based displays.

Phosphor materials are one type of fluorescent materials. Variousdescribed systems, devices and features in the examples that usephosphors as the fluorescent materials are applicable to displays withscreens made of other optically excitable, light-emitting, non-phosphorfluorescent materials, such as quantum dot materials that emit lightunder proper optical excitation (semiconductor compounds such as, amongothers, CdSe and PbS).

Examples of scanning beam display systems described here use at leastone scanning laser beam to excite color light-emitting materialsdeposited on a screen to produce color images. The scanning laser beamis modulated to convey image information for red, green and blue colorsor in other visible colors and is controlled in such a way that thelaser beam excites the color light-emitting materials in red, green andblue colors based on image data from the red, green and blue colorchannels of the image, respectively. Hence, the scanning laser beamcarries the image data but does not directly produce the visible lightseen by a viewer. Instead, the color light-emitting fluorescentmaterials on the screen absorb the energy of the scanning laser beam andemit visible light in red, green and blue or other colors to generateactual color images seen by the viewer.

Laser excitation of the fluorescent materials using one or more laserbeams with energy sufficient to cause the fluorescent materials to emitlight or to luminesce is one of various forms of optical excitation. Inother implementations, the optical excitation may be generated by anon-laser light source that is sufficiently energetic to excite thefluorescent materials used in the screen. Examples of non-laserexcitation light sources include various light-emitting diodes (LEDs),light lamps and other light sources that produce light at a wavelengthor a spectral band to excite a fluorescent material that converts thelight of a higher energy into light of lower energy in the visiblerange. The excitation optical beam that excites a fluorescent materialon the screen can be at a frequency or in a spectral range that ishigher in frequency than the frequency of the emitted visible light bythe fluorescent material. Accordingly, the excitation optical beam maybe in the violet spectral range and the ultra violet (UV) spectralrange, e.g., wavelengths under 420 nm. In the examples described below,UV light or a UV laser beam is used as an example of the excitationlight for a phosphor material or other fluorescent material and may belight at other wavelength. In the above and other displayimplementations, multiple display screens can be placed adjacent to oneanother in an array to form a larger display screen.

Referring to FIG. 1, an example of a laser-based display system using ascreen having color phosphor stripes is shown. Alternatively, colorphosphor dots or quantum dot or quantum dot regions may also be used todefine the image pixels on the screen. The illustrated system includes alaser module 110 to produce and project at least one scanning laser beam120 onto a screen 101. The screen 101 has parallel color phosphorstripes in the vertical direction where red phosphor absorbs the laserlight to emit light in red, green phosphor absorbs the laser light toemit light in green and blue phosphor absorbs the laser light to emitlight in blue. Each group of three adjacent color phosphor stripescontains stripes for the three different colors. One particular spatialcolor sequence of the stripes is shown in FIG. 2B as red, green andblue. Other color sequences may also be used.

The laser beam 120 is at the wavelength within the optical absorptionbandwidth of the color phosphors. The laser beam 120 can be at awavelength shorter than the visible blue, green and red colors for thecolor images. As an example, the color phosphors may be phosphors thatabsorb UV light in the spectral range from about 380 nm to about 420 nmto produce desired red, green and blue light.

The laser module 110 can include one or more lasers such as UV diodelasers to produce the beam 120, a beam scanning mechanism to scan thebeam 120 horizontally and vertically to render one image frame at a timeon the screen 101, and a signal modulation mechanism to modulate thebeam 120 to carry the information for image channels for red, green andblue colors. Such display systems may be configured as rear light enginesystems where the viewer and the laser module 110 are on the oppositesides of the screen 101. Alternatively, such display systems may beconfigured as front light engine systems where the viewer and lasermodule 110 are on the same side of the screen 101.

In the example scenario illustrated in FIG. 2A, the scanning laser beam120 is directed at the green phosphor stripe within a pixel to producegreen light for that pixel. FIG. 2B further shows the operation of thescreen 101 in a view along the direction B-B perpendicular to thesurface of the screen 101. Since each color stripe is longitudinal inshape, the cross section of the beam 120 may be shaped to be elongatedalong the direction of the stripe to maximize the fill factor of thebeam within each color stripe for a pixel. This may be achieved by usinga beam shaping optical element in the laser module 110.

The laser source that is used to produce a scanning laser beam thatexcites a phosphor material on the screen may be a single mode laser ora multimode laser. The laser may also be a single mode along thedirection perpendicular to the elongated direction phosphor stripes tohave a small beam spread that is confined by the width of each phosphorstripe. Along the elongated direction of the phosphor stripes, thislaser beam may have multiple modes to spread over a larger area than thebeam spread in the direction across the phosphor stripe. This use of alaser beam with a single mode in one direction to have a small beamfootprint on the screen and multiple modes in the perpendiculardirection to have a larger footprint on the screen allows the beam to beshaped to fit the elongated color subpixel on the screen and to providesufficient laser power in the beam via the multimodes to ensuresufficient brightness of the screen.

Accordingly, the laser beam 120, which is modulated to carry opticalpulses with image data, needs to be aligned with respect to proper colorpixels on the screen 101. The laser beam 120 is scanned spatially acrossthe screen 101 to hit different color pixels at different times.Accordingly, the modulated beam 120 carries the image signals for thered, green and blue colors for each pixel at different times and fordifferent pixels at different times. Hence, the beams 120 are coded withimage information for different pixels at different times. The beamscanning thus maps the timely coded image signals in the beams 120 ontothe spatial pixels on the screen 101.

Referring now to FIG. 3, an example implementation of the laser module110 in FIG. 1 is illustrated. A laser array 310 with multiple lasers isused to generate multiple laser beams 312 to simultaneously scan thescreen 101 for enhanced display brightness. A signal modulationcontroller 320 is provided to control and modulate the lasers in thelaser array 310 so that the laser beams 312 are modulated to carry theimage to be displayed on the screen 101. The signal modulationcontroller 320 can include a digital image processor that generatesdigital image signals for the three different color channels and laserdriver circuits that produce laser control signals carrying the digitalimage signals. The laser control signals are then applied to modulatethe lasers, e.g., the currents for laser diodes, in the laser array 310.

The beam scanning can be achieved by using a scanning mirror 340 such asa galvo mirror for the vertical scanning and a multi-facet polygonscanner 350 for the horizontal scanning A scan lens 360 can be used toproject the scanning beams form the polygon scanner 350 onto the screen101. The scan lens 360 is designed to image each laser in the laserarray 310 onto the screen 101. Each of the different reflective facetsof the polygon scanner 350 simultaneously scans N horizontal lines whereN is the number of lasers.

In the illustrated example, the laser beams are first directed to thegalvo mirror 340 and then from the galvo mirror 340 to the polygonscanner 350. The output scanning beams 120 are then projected onto thescreen 101. A relay optics module 330 is placed in the optical path ofthe laser beams 312 to modify the spatial property of the laser beams312 and to produce a closely packed bundle of beams 332 for scanning bythe galvo mirror 340 and the polygon scanner 350 as the scanning beams120 projected onto the screen 101 to excite the phosphors and togenerate the images by colored light emitted by the phosphors.

The laser beams 120 are scanned spatially across the screen 101 to hitdifferent color pixels at different times. Accordingly, each of themodulated beams 120 carries the image signals for the red, green andblue colors for each pixel at different times and for different pixelsat different times. Hence, the beams 120 are coded with imageinformation for different pixels at different times by the signalmodulation controller 320. The beam scanning thus maps the time-domaincoded image signals in the beams 120 onto the spatial pixels on thescreen 101. For example, the modulated laser beams 120 can have eachcolor pixel time equally divided into three sequential time slots forthe three color subpixels for the three different color channels. Themodulation of the beams 120 may use pulse modulation techniques toproduce desired grey scales in each color, a proper color combination ineach pixel, and desired image brightness.

In one implementation, the multiple beams 120 are directed onto thescreen 101 at different and adjacent vertical positions with twoadjacent beams being spaced from each other on the screen 101 by onehorizontal line of the screen 101 along the vertical direction. For agiven position of the galvo mirror 340 and a given position of thepolygon scanner 350, the beams 120 may not be aligned with each otheralong the vertical direction on the screen 101 and may be at differentpositions on the screen 101 along the horizontal direction. The beams120 can only cover one portion of the screen 101. At a fixed angularposition of the galvo mirror 340, the spinning of the polygon scanner350 causes the beams 120 from N lasers in the laser array 310 to scanone screen segment of N adjacent horizontal lines on the screen 101. Atend of each horizontal scan over one screen segment, the galvo mirror340 is adjusted to a different fixed angular position so that thevertical positions of all N beams 120 are adjusted to scan the nextadjacent screen segment of N horizontal lines. This process iteratesuntil the entire screen 101 is scanned to produce a full screen display.

The stripe design in FIG. 2B for the fluorescent screen 101 in FIGS. 1and 3 can be implemented in various configurations. FIG. 2A shows oneexample which places the fluorescent layer 203 such as a color phosphorstripe layer between two substrates 201 and 202. In a rear projectionsystem, it may be desirable that the screen 101 couple as much light aspossible in the incident scanning excitation beam 120 into thefluorescent layer with while maximizing the amount of the emitted lightfrom the fluorescent layer that is directed towards the viewer side. Anumber of screen mechanisms can be implemented, either individually orin combination, in the screen 101 to enhance the screen performance,including efficient collection of the excitation light, maximization offluorescent light directed towards the viewer side, enhancement of thescreen contrast and reduction the screen glare. The structure andmaterials of the screen 101 can be designed and selected to meetconstraints on cost and other requirements for specific applications.

FIG. 4 illustrates an example screen 101 having a fluorescent layer 400with fluorescent stripes for emitting red, green and blue colors underoptical excitation of the scanning excitation light. A number of screenfeatures are illustrated as examples and can be selectively implementedin specific screens. Hence, a particular fluorescent screen having onlysome of the features illustrated in FIG. 4 may be sufficient for aparticular display application.

The fluorescent layer 400 includes parallel fluorescent stripes withrepetitive color patterns such as red, green and blue phosphor stripes.The fluorescent stripes extend perpendicular to the horizontal scandirection of the scanning excitation beam 120 shown in FIG. 1. Asillustrated in FIG. 4 and in FIG. 2B, each display pixel on the screenincludes three subpixels which are portions of adjacent red, green andblue stripes 401, 402 and 402. The dimension of each subpixel along thehorizontal direction is defined by the width of each stripe and thedimension along the vertical direction is defined by the beam widthalong the vertical direction.

A stripe divider 404 may be formed between any two adjacent fluorescentstripes to minimize or reduce the cross talk between two adjacentsubpixels. As a result, the smearing at a boundary between two adjacentsubpixels within one color pixel and between two adjacent color pixelscan be reduced, and the resolution and contrast of the screen can beimproved.

In some implementations, the stripe divider is a low-index material(i.e., lower index of refraction than the material of the stripe). Forexample, each stripe can be separated from an adjacent stripe by an airgap.

If the stripe divider is a solid material, it can be opticallyreflective and opaque, or optically absorbent. In some implementations,the stripe divider is comparable or higher index material than thestripe, but is optically reflective and opaque or optically absorbent.The sidewalls of each stripe divider 404 can be made opticallyreflective to improve the brightness of each subpixel and the efficiencyof the screen.

The fluorescent layer 400 is an optically active layer in the contextthat the excitation light at the excitation wavelength is absorbed bythe fluorescent materials and is converted into visible fluorescentlight of different colors for displaying the images to the viewer. Inthis regard, the fluorescent layer 400 is also the division between the“excitation side” and the “viewer side” of the screen where the opticalproperties of the two sides are designed very differently in order toachieve desired optical effects in each of two sides to enhance thescreen performance. Examples of such optical effects include, enhancingcoupling of the excitation beam 120 into the fluorescent layer,recycling reflected and scattered excitation light that is not absorbedby the fluorescent layer 400 back into the fluorescent layer 400,maximizing the amount of the emitted visible light from the fluorescentlayer 400 towards the viewer side of the screen, reducing screen glareto the viewer caused by reflection of the ambient light, blocking theexcitation light from existing the screen towards the viewer, andenhancing the contrast of the screen. Various screen elements can beconfigured to achieve one or more of these optical effects. Severalexamples of such screen elements are illustrated in FIG. 4.

The fluorescent screen 101 in FIG. 4 can include a substrate layer 424to provide a rigid structural support for various screen components.This substrate layer 424 can be a thin substrate or a rigid sheet. Whenplaced on the viewer side of the fluorescent layer 400 as illustrated inFIG. 4, the substrate layer 424 can be made of a material transparent orpartially transparent to the visible colored light emitted by thefluorescent stripes 401, 402, 403. A partial transparent material canhave a uniform attenuation to the visible light including the threecolors emitted by the fluorescent stripes to operate like an opticalneutral density filter. The substrate layer 424 can be made of a plasticmaterial, a glass material, or other suitable dielectric material. Forexample, the substrate layer 424 may be made of an acrylic rigid sheet.The thickness of the substrate layer 424 may be a few millimeters insome designs. In addition, the substrate layer 424 may be madereflective and opaque to the excitation light of the excitation beam 120to block the excitation light from reaching the viewer and to recyclethe unabsorbed excitation light back to the fluorescent layer 400.

The substrate layer 424 can also be located on the excitation side ofthe fluorescent layer 400. Because the excitation beam 120 must transmitthrough the substrate layer 424 to enter the fluorescent layer 400, thematerial for the substrate layer 424 should be transparent to theexcitation light of the excitation beam 120. In addition, the substratelayer 424 in this configuration may also be reflective to the visiblelight emitted by the fluorescent layer 400 to direct any emitted visiblelight coming from the fluorescent layer 400 towards the viewer side toimprove the brightness of the displayed images.

In some implementations, the substrate layer 424 is not used or can beconsidered part of another component. For example, if the dichroic layerD1 412 is sufficiently rigid to support the components, then a separatesubstrate layer 424 may not be needed. In some implementations thecomponents might only be supported by dichroic layer D1 412, with thedichroic layer being flexible or even rollable.

Referring further to FIG. 4, at the entry side of the screen facing theexcitation beam 120, an entrance layer 411 can be provided to couple theexcitation beam 120 into the screen 101. The entrance layer 411 can be asolid layer having smooth surfaces on both the viewer and excitationsides. For example, the entrance layer can be a layer of polyethyleneterephthalate (PET).

In some implementations, servo marks may be formed, e.g., printed, onthe excitation side of the entrance layer 411. The servo marks have adifferent reflectivity than the remaining excitation-side surface of theentrance layer 411, e.g., the servo marks can be more reflective. Theservo marks can be specularly or diffusively reflective. A sensor candetect portion of the excitation beam reflected from the servo marks,and use this information to adjust timing of the modulation of theexcitation beam. The servo marks can be aligned with the stripe dividers404.

In some implementations, the entrance layer 411 can include a Fresnellens layer to control the incidence direction of the scanning excitationbeam 120. Alternatively or in addition, a prismatic layer or ahigh-index dielectric layer can also be used as part of the entrancelayer 411 to recycle light back into the screen including the excitationlight and the emitted visible light by the fluorescent layer. However,the entrance layer 411 can be omitted or provide the substrate layer.

To improve the brightness of the screen to the viewer, a first dichroiclayer 412 (D1) can be placed in the path of the excitation beam 120upstream from the fluorescent layer 400 to transmit light at thewavelength of the excitation beam 120 and to reflect visible lightemitted by the fluorescent layer 400. The first dichroic layer 412 canreduce the optical loss of the fluorescent light and thus enhances thescreen brightness. The first dichroic layer 412 can be provided by astack of coextruded polymer layers.

On the viewer side of the fluorescent layer 400, a second dichroic layer421 (D2) can be provided to transmit the visible light emitted by thefluorescent layer 400 and to reflect light at the wavelength of theexcitation beam 120. Hence, the second dichroic layer 421 can recyclethe excitation light that passes through the fluorescent layer 400 backto the fluorescent layer 400 and thus increases the utilizationefficiency of the excitation light and the screen brightness. The seconddichroic layer 421 can be provided by a stack of coextruded polymerlayers.

On the viewer side of the fluorescent layer 400, an optional contrastenhancement layer 422 can be included to improve the screen contrast.The contrast enhancement layer 422 can include color-selective absorbingstripes that spatially correspond to and align with fluorescent stripesin the fluorescent layer 400 along the direction perpendicular to thescreen layers. The color-selective absorbing stripes therefore transmitlight in respective colors of the fluorescent stripes and absorb lightin colors of other fluorescent stripes, respectively. Alternatively, thecontrast enhancement layer 422 can be an optical neutral density filterlayer that uniformly attenuates the visible light to reduce the glare ofthe screen due to the reflection of the ambient light. This neutraldensity filtering function may also be implemented in one or more otherlayers on the viewer side of the fluorescent layer 400, including thesubstrate layer 424.

In addition, the screen can include a screen gain layer 423 on theviewer side of the fluorescent layer 400 to optically enhance thebrightness and viewing angle of the screen. The gain layer 423 mayinclude a lenticular layer with lens elements, a diffractive optic layerof diffractive elements, a holographic layer with holographic elements,or a combination of these and other structures.

Furthermore, an excitation blocking layer 425 can be placed on theviewer side of the fluorescent layer 400 to block any excitation lightfrom exiting the screen to the viewer side. This layer can beimplemented by a material that transmits the visible light and absorbsthe excitation light. For example, a polyester based color filter can beused as this layer to block the excitation light which may be radiationfrom 400-415 nm. In some implementations, this blocking filter may havetransmission below 410 nm less than 0.01%, while having greater than 50%transmission above 430 nm. The neutral density filtering function canalso be incorporated in this layer, e.g., having a uniform attenuationto the visible light between 430 nm and 670 nm. This blocking functioncan be incorporated into the substrate layer 424.

The spatial sequence of the layers 421-425 on the viewer side of thefluorescent layer 400 may be different from what is shown in FIG. 4.

Referring now to FIG. 5, an example fluorescent layer 500 formed on asupporting substrate 502 is shown. The fluorescent layer 500 can providethe fluorescent layer 400 from FIG. 4. The fluorescent layer 500 caninclude parallel fluorescent stripes. The stripes can be arranged in apattern, for example, with three adjacent stripes 504, 506, 508 foremitting blue, green, and red light, respectively. The stripes in thefluorescent layer 500 need not be totally flat, e.g., they may haverounded corners or have an oval cross-section.

The substrate 502 may be a rigid substrate, or alternatively, may be aflexible sheet. In some cases, the substrate 502 may be a dichroicfilter layer (e.g. a color mirror, or CM, layer), that can passexcitation light while reflecting visible light. Thus, the substrate 502can provide the first dichroic layer 412 and/or substrate 424 from FIG.4. As a dichroic filter, the substrate 502 can be formed of co-extrudedpolymer layers of alternating high and low refractive index. In somecases, the substrate 502, as well as the fluorescent layer 500 that isattached to the substrate 502, may be sufficiently flexible that it canbe wound around a roller. For example, the resulting flexibility of thesubstrate 502 and the attached fluorescent layer 500 may be such thatthey can be rolled around a roller having a diameter as low as 25 mmwithout damage to the assembly. In some cases, the substrate 502 may bea CM layer having a thickness of approximately 90 μm.

In particular, referring to FIGS. 3 and 4, the substrate 502 can includeboth the dichroic filter layer 412 and the entrance layer 411. Theentrance layer 411 can be a polymer layer, e.g., a layer of polyethyleneterephthalate (PET), with smooth surfaces on the viewer and excitationsides. The dichroic filter later 412 can be attached to a substratelayer 424 by a pressure sensitive adhesive layer.

As illustrated in FIGS. 5 and 6, the fluorescent layer 500 (made up inthis instance of stripes 504, 506, 508) are supported at their underside(i.e., the excitation side) by an attachment layer 512 that attaches theexcitation side of the fluorescent layer 500 to the substrate 502.

In the illustrated implementation, the attachment layer 512 is made upof a plurality of attachment stripes 510 that each support an edgeregion of the corresponding fluorescent stripes 504, 506, 508. Suchattachment layer, in this case the attachment stripes 510, has asufficient thickness to provide vertical separation between thefluorescent layer 500 and the substrate layer 502. Accordingly, air gaps610 are formed between the fluorescent layer 500 and the substrate layer502 in regions not occupied by the attachment layer. Unsupportedportions of the fluorescent layer 500 may sag or deform, and may come incontact with the underlying substrate layer 502. In some cases, suchsagging or deformation can lead to a breakage in the fluorescent layer500. However, selection of a sufficiently thick attachment stripe canaccommodate the sag and reduce the likelihood that the portion of thefluorescent layer contact the substrate layer 502. In some cases, if theattachment stripes 510 are too soft, they can deform under the weight ortension of the fluorescent layer 500, causing portions of thefluorescent layer 500 to sag or deform along with the attachment stripes510. To prevent this, the attachment stripes 510 should be sufficientlyfirm so as to avoid the fluorescent layer contacting the substrate layer502, e.g., to undergo substantially no deformation when supporting thefluorescent layer. For example, UV curable resin may be used.

The “air gaps” between the fluorescent layer 500 and the substrate 502can be filled with a gas, or there may be a vacuum in the gaps 610. Thegas can be air, or a substantially pure gas, e.g., nitrogen. As furtherdescribed below (see FIGS. 7A-7E), the attachment layer can be providedin various configurations other than the stripes 510. In some cases, theair gaps 610 may be filled with polymer or other non-gaseous materialshaving an index lower than that of the fluorescent layer 500.

The air gaps 610 (see FIG. 6) can allow excitation light emerging fromthe viewer side of the substrate 502 to reach the fluorescent layer 500without propagating through another intermediary material. Such gapsthat exist immediately below the fluorescent layer can help increasebrightness, reduce light piping, and reduce cross-talk, among otherpotential benefits. By using the gaps to reduce light piping, which canoccur when the phosphor touches the underlying substrate, lightemanating from the phosphor can more efficiently reflect off thesubstrate to better reach the viewer. The attachment stripes 510, aswell as other configurations of the attachment layer, can be made from aflexible material. In some cases, the attachment layer can be formedfrom a resin that is UV cured. The resin may be chosen so after curingit is transparent to the excitation light. In some cases, the resin maybe chosen so after curing it is opaque to visible light.

Referring further to FIG. 6, an example fluorescent screen 101 includesthe substrate layer 502, the fluorescent layer 500 that is attached tothe substrate layer 502 via the attachment layer 512, and a coversubstrate 602 that is attached to the viewer side of the fluorescentlayer 500 via an adhesive layer 616.

The cover substrate 602 can provide the substrate 424 and/or excitationblocking layer 425 from FIG. 4. For example, the cover substrate 602 caninclude a polymer film 620, e.g., polyethylene terephthalate (PET).Various gain/enhancement/filter layers may be included on the viewerside of the fluorescent layer 500 (see, e.g., FIG. 4).

For example, the viewer side of the film 620 can be coated with a UVblocking layer 622 to help prevent or mitigate UV light from reachingthe viewer. The UV blocking layer 622 should be non-yellowing to UVexcitation.

As another example, the excitation side of the film 620 can be coatedwith a protective coating 624. The protective coating 625 can be a UVblocking layer. For example, a laser-stable red-shifted UV absorber,e.g., CarboProtect®, can be used to block the excitation light.Alternatively, or additionally, other protective or functional coatingssuch as hard coats, antiglare coats, anti-fingerprint coats, amongothers, may be used.

As shown in FIG. 6, the attachment layer 512 that is sandwiched betweenthe fluorescent layer 500 and the substrate layer 502, in this caseattachment stripes 510, help attach the excitation side of thefluorescent layer 500 to the viewer side of the substrate layer 502.Moreover, by being laterally spaced apart (i.e. by defining laterallyspaced-apart regions) and by having a sufficient thickness to accountfor any variations in surface flatness of the surrounding layers, theattachment stripes 510 can help form air gaps 610 on the excitation sideof the fluorescent layer 500. The thickness of the attachment layerhelps determine the thickness of the resulting air gap 610, alsoreferred to as excitation side air gaps 610. For example, the attachmentlayer may have a thickness of 10 μm, thereby creating an approximately10 μm separation between the fluorescent layer 500 and the substratelayer 502.

On the viewer side, the cover substrate 602 can be attached to thefluorescent layer 500 via the adhesive layer 616. The adhesive layer616, which can include a patterned layer of PSA (pressure sensitiveadhesive), attaches the cover substrate 602 to the fluorescent layer 500while ensuring separation between the excitation side of the coversubstrate 602 and the viewer side of the fluorescent layer 500.

The thickness of the adhesive layer 616 is sufficient that air gaps 612,also referred to as viewer side air gaps 612, are formed between thecover substrate 602 in regions where the adhesive layer is absent. Thethickness of the adhesive layer 616 can be selected to provide theviewer-side air gaps 612 on the viewer side of the fluorescent layer 500while still accounting for any surface variations in the fluorescentlayer 500. For example, the adhesive layer 616 can be betweenapproximately 5 μm and 25 μm thick. The fluorescent layer 500 can have athickness of between approximately 5 μm and 50 μm. The viewer side airgaps 612 can help, for example, reduce undesired image halo and enablethe UV to be recycled back to the fluorescent layer 500 to increase theoptical efficiency. The viewer side air gaps 612 can be filled with agas, e.g., air or nitrogen, or there may be a vacuum in the viewer-sidegaps 612.

The adhesive layer 616 can be made from PSA that exhibits minimalmaterial flowing and good bonding strength between the fluorescent layer500 and the cover substrate 602 (or any other layer that the viewer sideof the fluorescent layer 500 is directly attached to). Additionally, theadhesive layer 616 can be made from PSA or other adhesive material thatis of optical grade so as to optimize the visible light emanating fromthe excited phosphor and not introduce spurious light. Additionally, theadhesive layer 616 can be made from PSA that does not absorb UV light at405 nm so as to reduce cross talk between the phosphor regions in thefluorescent layer 500.

In some implementations, the phosphor stripes 504, 506, 508 are to bespaced apart from each other in the plane of the fluorescent screen 500by air gaps 614, also referred to as in-plane air gaps 614. The in-planeair gaps 614 can be filled with a gas, e.g., air or nitrogen, or theremay be a vacuum in the viewer-side gaps 614. In some cases, the air gaps614 may be filled with polymer or other non-gaseous materials having anindex lower than that of the fluorescent layer 500.

By (i) creating separation in the out-of-plane direction between thefluorescent layer 500 and the substrate layer 500 using the attachmentlayer (e.g. attachment stripes 510) to create excitation side air gaps610, by (ii) creating separation in the out-of-plane direction betweenthe fluorescent layer 500 and the PET layer 602 using the adhesive layer616 to create viewer side air gaps 612, and by (iii) creating separationbetween the phosphor stripes 504, 506, 508 of the fluorescent layer 500to form in-plane air gaps 614, the amount of material that touches thephosphor stripes 504, 506, 508 can be minimized, thereby improving thedisplayed image by, among other things, increasing brightness, reducinglight piping, and reducing cross-talk.

Referring now to FIGS. 7A to 7E, the attachment layer that attaches theexcitation side of the fluorescent layer 500 to an underlying substrate(e.g. substrate 502) while providing a vertical separation therebetweensuch that air gaps are formed underneath the fluorescent layer, can takevarious forms. In general, in these various implementations, theattachment regions of the attachment layer are positioned at the edgesof the fluorescent stripes 504, 506, 508, e.g., the outer 25% of thewidth on each side of the stripe. Conversely, the attachment regions arepresent in a center region of a stripes, e.g., the center half of thewidth of the stripe. In some implementations, the attachment regions arelocated only in the outer 10% of the width on each side of the stripe.

In FIGS. 7A-7B, the attachment stripes 510 are shown bridging the gapbetween phosphor stripes 504, 506, 508 that are disposed in spaced-apartfashion. The attachment stripes 510 extend in parallel to thefluorescent stripes.

As illustrated, each of the attachment stripes 510 should be narrowenough to increase the area of the excitation side of the phosphorstripes 504, 506, 508 is are exposed to provide for improvedtransmission of the excitation light to the fluorescent stripes, whileremaining wide enough to provide structural support to the correspondingphosphor stripes 504, 506, 508. The attachment stripes 510 may be spacedat a pitch that corresponds to the pixel width of the pixel element. Forexample, if each of the phosphor stripes are spaced at a pitch of 500 μmto 550 μm to thereby result in the pixel width of approximately 1500 μm,the attachment stripes 510 may also be spaced at a pitch of betweenapproximately 500 μm and 550 μm. To prevent formation of a moirépattern, the pitch of the pixel element and the pitch of the adhesivestripes should be such that they do not result in superimposed patterns.

In FIG. 7B, the attachment stripes 510 are shown having a greater widththan in FIG. 7A, thereby covering a larger portion of the phosphorstripes 504, 506, 508 from incoming excitation light. As illustrated,each of the attachment stripes 510 support and overlap with an edgeregion of each of the phosphor stripes 504, 506, 508. A width We of theoverlapping edge region should be minimized to ensure optimizedperformance but should be wide enough to provide adequate structuralsupport to the phosphor stripes 504, 506, 508 while accounting formanufacturing/alignment tolerance. For example, We can be around 30 μm.A width Wp, which corresponds to the width of the exposed region of thephosphor stripes 504, 506, 508 at the excitation side, should bemaximized for optimized performance. In other words, the area percentageof the phosphor stripes 504, 506, 508 that is exposed to incomingexcitation light, which in this case can be shown by the expressionWp/(Wp+2We), should be maximized. For example, the area percentageshould be above 50% to ensure that enough excitation light impingesdirectly on the excitation of the phosphor stripes 504, 506, 508 aftergoing through the excitation side air gaps 610. In some cases, the areapercentage should be at or above 90% for superior performance.

Attachment stripes 510 that are transparent to the excitation light maybe advantageous in that they can be made wider than opaque attachmentstripes without adversely affecting the amount of excitation light thatimpinges on the phosphor layer. On the other hand, having an opaqueattachment stripes may be advantageous as it can help stop excitationlight from reaching the viewer without the need for a separate blockingfilm. In addition, the opaque layer can be very effective at blockingpiping through to the excitation-side substrate that supports thephosphor layer. In some cases, the attachment stripes may be partiallyopaque. For example, the attachment stripe layer may be transparent butinclude opaque particles.

Although FIGS. 7A and 7B illustrate the attachment stripes 510 asbridging the gap between fluorescent stripes, this is not necessary. Forexample, each attachment stripe 510 could be positioned under an edge ofa fluorescent stripes. The attachment stripe 510 could be positionedonly under the fluorescent stripe, or extend partially past the edge ofthe fluorescent stripe without bridging the gap between fluorescentstripes.

FIG. 7C shows attachment patches 520, which are similar to theattachment stripes 510 but differ in that they don't run along an entirelength of the phosphor stripes. By supporting the phosphor stripes atjust select locations along the edge regions as opposed to along anentire length of the edge regions, the size of the air gaps formed onthe excitation side of the fluorescent layer may be increased. In somecases, as shown in FIG. 7D, attachment patches 522 having round or othershapes can be used.

In some cases, as shown in FIG. 7E, the attachment layer can includeattachment posts 524 that are narrower in width than the in-plane gapsthat separate the phosphor stripes 502, 504, 506. In such cases, theattachment posts 524 may be positioned at various locations within thephosphor stripes 502, 504, 506 to thereby attach the excitation side ofthe fluorescent layer to the underlying substrates. In such cases, thesizes of the attachment posts 524 should be kept small to ensure that aminimal area of the phosphor stripes 502, 504, 506 is touched by theattachment posts 524 while providing sufficient structural support tothe corresponding fluorescent stripe. As illustrated in FIG. 7F,attachment posts 524 may be randomly distributed between the fluorescentlayer and the underlying substrate.

In some cases, as shown in FIG. 7G, an attachment stripe 526 may beoriented transverse (e.g. perpendicular) to the phosphor stripes. Asshown in FIG. 7H, an attachment stripe 528 may include curved portions.A combination of the attachment layer variations illustrated in FIGS.7A-7H, as well as other similar variations, may be used to attach thephosphor layer to the substrate while maintaining the air gap 610 on theexcitation side of the phosphor layer.

Referring now to FIG. 8, the adhesive layer 616 on the viewer side ofthe fluorescent layer can have a pattern that is adapted to reduce moirépatterns that might otherwise be produced, for example, when imagespresented the display screen are captured by a digital image capturingdevice having a periodic light-sensing structure. Such moiré patternsmay be produced due to the interference between the periodiclight-emitting structures (e.g., periodic arrays of coloredlight-emitting pixels and/or sub-pixels) in the display device and theperiodic light-sensing structures (e.g., periodic arrays ofphoto-sensors) in the image capturing device.

For instance, the anti-moiré pattern of the adhesive layer 616 mayincorporate periodicity that does not line up with the periodicity ofthe phosphor stripes 502, 504, 506. In some cases, as shown in FIG. 8,the adhesive layer 616 may have a cross hatch pattern with roundedcorners to minimize any alignment with the phosphor stripes. In somecases, the adhesive layer 616 may incorporate a sinusoidal pattern. Insome cases, the adhesive layer 616 may include random or quasi-randomelements to further eliminate any undesired alignment and periodicitythat may give rise to moiré patterns in the displayed image or a digitalcapture thereof.

In some implementations, the adhesive layer 616 may have patternssimilar to those on the excitation side of the fluorescent layer, forexample as shown in FIGS. 7A-7H. Alternatively, the adhesive layer 616may include a sawtooth pattern, a honeycomb pattern, and variousoverlapping or non-overlapping waver patterns.

FIGS. 9A to 9D illustrate example variations to the cross-hatchanti-moiré pattern shown in FIG. 8. In FIG. 9A, the represented linespacing is 3 mm while the represented line width is 0.15 mm. For FIG.9B, the corresponding values are 3 mm and 0.2 mm, thus indicating theuse of a thicker (in the in-plane direction) of the adhesive layer 616.In FIG. 9C, the shown line spacing represents 5 mm while the shown linewidth is 0.15 mm. Compared to the patterns shown in FIGS. 9A and 9B, thelines in FIG. 9C are spaced farther part, thereby reducing the amount ofbond area provided by the attachment layer. For FIG. 9D, thecorresponding values represented are 5 mm and 0.2 mm. For FIGS. 9A to9D, the sample patterns represent bond areas of 11.5%, 15.3%, 7.0%, and9.3%, respectively.

While this document contains many specifics, these should not beconstrued as limitations on the scope of an invention or of what may beclaimed, but rather as descriptions of features specific to particularembodiments of the invention. Certain features that are described inthis document in the context of separate implementations can also beimplemented in combination in a single implementation. Conversely,various features that are described in the context of a singleimplementation can also be implemented in multiple implementationsseparately or in any suitable subcombination. Moreover, althoughfeatures may be described above as acting in certain combinations andeven initially claimed as such, one or more features from a claimedcombination can in some cases be excised from the combination, and theclaimed combination may be directed to a subcombination or a variationof a subcombination.

Only a few implementations are disclosed. However, it is understood thatvariations, enhancements, and other implementations can be made based onwhat is described and illustrated in this application.

For example, although multiple colors have been described, thetechniques are applicable to a monochromatic system. Although thedescription focuses on color phosphors, the stripe can be otherfluorescent materials, such as quantum dots. Although the descriptionfocuses on a laser for the excitation beam, other collimated light beamscould be used, and the excitation beam could also be in the visiblelight range rather than UV. Although a rotating polygon is described forscanning the excitation beams, other kinds of scanners could be used,e.g., two mirror galvos could be used to deflect the excitation beams intwo perpendicular directions.

What is claimed is:
 1. A display screen comprising: a filter layerhaving a first side and an opposing second side; a fluorescent layerincluding a plurality of parallel fluorescent stripes; and an attachmentlayer positioned between an excitation side of the fluorescent layer andthe first side of the filter layer that attaches the excitation side offluorescent layer to the filter layer while providing verticalseparation between the fluorescent layer and the filter layer, theattachment layer including a plurality of attachment regions that areseparated from each other by one or more lateral spacings such that oneor more excitation-side air gaps are formed between areas of thefluorescent layer and the filter layer with the one or moreexcitation-side air gaps extending to excitation side surfaces of thefluorescent stripes, wherein, during display operation, excitation lightreceived on the second side of the filter layer propagates through tothe first side of the filter layer, and at least a portion of theexcitation light that propagates from the second side of the filterlayer travels through the one or more excitation-side air gaps to excitethe fluorescent stripes.
 2. The display screen of claim 1, wherein theattachment layer includes a plurality of attachment stripes that contactthe excitation side surfaces of the fluorescent stripes at their edgeregions.
 3. The display screen of claim 2, wherein the plurality ofattachment stripes extend parallel to the fluorescent stripes.
 4. Thedisplay screen of claim 3, wherein the plurality of attachment stripesbridge spaces between adjacent fluorescent stripes.
 5. The displayscreen of claim 2, wherein the plurality of attachment stripes extendtransverse to the fluorescent stripes.
 6. The display screen of claim 2,further comprising: a sheet layer having a first side and an opposingsecond side; and an adhesive layer positioned between a viewer side ofthe fluorescent layer and the second side of the sheet layer to attachthe viewer side of fluorescent layer to the sheet layer while providingvertical separation between the fluorescent layer and the sheet layer,the adhesive layer defining openings such that one or more viewer-sidesecond air gaps are formed between areas of the fluorescent layer andthe sheet layer that correspond to the one or more openings in theadhesive layer, wherein, during display operation, at least a portion ofthe fluorescent light that emanates from the fluorescent layer travelsthrough the one or more viewer-side air gaps.
 7. The display screen ofclaim 1, wherein the attachment layer is formed from a UV-curable resin.8. The display screen of claim 1, wherein the attachment regions arepositioned to not overlap with center regions of the fluorescentstripes.
 9. The display screen of claim 1, wherein the plurality offluorescent stripes are spaced apart from each other by distances suchthat in-plane air gaps extending the distances are formed betweenadjacent fluorescent stripes.
 10. The display screen of claim 9, whereinthe attachment layer includes a plurality of attachment posts narrowerin width than the in-plane air gaps that separate the fluorescentstripes.
 11. The display screen of claim 1, comprising: a sheet layerhaving a first side and an opposing second side; and an adhesive layerpositioned between a viewer side of the fluorescent layer and the secondside of the sheet layer to attach the viewer side of fluorescent layerto the sheet layer while providing vertical separation between thefluorescent layer and the sheet layer, the adhesive layer definingopenings such that one or more viewer-side air gaps are formed betweenareas of the fluorescent layer and the sheet layer that correspond tothe one or more openings in the adhesive layer, wherein, during displayoperation, at least a portion of the fluorescent light that emanatesfrom the fluorescent layer travels through the one or more viewer-sideair gaps.
 12. The display screen of claim 11, wherein the adhesive layerhas an anti-aliasing pattern configured to reduce moiré patterns in animage displayed on the display screen.
 13. The display screen of claim12, wherein the plurality of fluorescent stripes are spaced apart fromeach other such that in-plane second air gaps are formed betweenadjacent fluorescent stripes.
 14. The display screen of claim 12,wherein the adhesive layer includes a cross-hatch pattern.
 15. Thedisplay screen of claim 12, wherein the adhesive layer includes asinusoidal pattern.
 16. The display screen of claim 1, wherein theattachment layer includes a plurality of attachment stripes that extendperpendicular to the fluorescent stripes.
 17. A display screencomprising: a filter layer having a first side and an opposing secondside; a fluorescent layer including a plurality of parallel fluorescentstripes; and an attachment layer positioned between an excitation sideof the fluorescent layer and the first side of the filter layer thatattaches the excitation side of fluorescent layer to the filter layerwhile providing vertical separation between the fluorescent layer andthe filter layer, the attachment layer including a plurality ofattachment regions that underlie a first region of the fluorescentstripes and that are separated from each other by one or more lateralspacings, wherein one or more excitation-side low-index gaps are formedin the one or more lateral spacings in between areas of the fluorescentlayer and the filter layer with the one or more excitation-sidelow-index gaps extending to excitation side surfaces of the fluorescentstripes, the low-index gaps underlying a second region of thefluorescent stripes different from the first region of the fluorescentstripes, wherein, during display operation, excitation light received onthe second side of the filter layer propagates through to the first sideof the filter layer, and at least a portion of the excitation light thatpropagates from the second side of the filter layer travels through theone or more excitation-side low-index gaps to excite the fluorescentstripes.
 18. The display screen of claim 17, wherein the low-index gapspartially underlie spaces between adjacent fluorescent stripes.
 19. Thedisplay screen of claim 18, wherein the low-index gaps occupy spacesbetween adjacent fluorescent stripes.
 20. The display screen of claim17, wherein the low-index gaps are air gaps.